This invention relates to electron beam lithography, or similar systems in which a workpiece is treated in a high vaccum chamber.
Because of the expense of such systems it is important that their active operation time be maximized. It is thus desirable to minimize the downtime associated with loading workpieces into and out of the system.
Typically, some form of vacuum lock is used for loading workpieces.
Thus, in Hasson et al. U.S. Pat. No. 3,874,525, wafers are interchanged between an antechamber and an x-y table, and between the antechamber and the atmospheric pressure exterior.
In other prior art systems separate antechambers are used for loading and unloading wafers.
In yet another prior art system a single antechamber is arranged to receive two wafers simultaneously. An elevator is then used to cycle the wafers to and from the x-y table.
The possibility of loading a magazine of, say, four to ten cassettes into such an antechamber has also been disclosed, with suggested use of a roughing vacuum chamber in series with the antechamber. With a magazine in place, the roughing chamber would be pumped down to a rough vacuum. The magazine would then be transferred to the high vacuum antechamber.